The aim of this research is to extend our understanding of the biochemical basis of inflammation. We will approach this goal by designing peptides which can serve as substrates, inhibitors, and affinity ligands for purification of the C3 and C5 convertases, key enzymes in complement-mediated inflammation. Peptides will be synthesized by the Merrifield method of solid-phase peptide synthesis. Substrate activity will be measured by the use of fluorescent and radiolabled substrates. Inhibition will be measured by inhibition of the cleavage of synthetic substrates, by inhibition of complement mediated hemolysis, and by inhibition of cleavage of radiolabeled C3 and C5. The involvement of the C3 and C5 convertases in pathology, will be investigated by localization of active convertases in cryostat frozen sections by their cleavage of fluorogenic substrates.